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MATERIALS CHEMISTRY | RESEARCH ARTICLE

Green tea leaves mediated ZnO nanoparticlesand its antimicrobial activityShagufta Irshad, Amna Salamat, Aftab Ahmed Anjum, Saba Sana, Rahman ShahZaib Saleem,Azra Naheed and Asia Iqbal

Cogent Chemistry (2018), 4: 1469207

MATERIALS CHEMISTRY | RESEARCH ARTICLE

Green tea leaves mediated ZnO nanoparticlesand its antimicrobial activityShagufta Irshad1*, Amna Salamat1, Aftab Ahmed Anjum2, Saba Sana2,Rahman ShahZaib Saleem3, Azra Naheed1 and Asia Iqbal4

Abstract: Plant-mediated synthesis of ZnO Nanoparticles (NPs) have multiple advan-tages over conventional synthetic methods like easy, inexpensive, eco-friendly, nontoxicby-products and no critical conditions of temperature and pressure required. In thisstudy, 9.1 g ZnO NPs were synthesized from 230mL of 0.2 M Zinc acetate dihydrate and100 mL of green tea leaves extract at room temperature (25°C). The leaves extract wasprepared by heating 10gm dried leaves in 100mL of deionized distilled water at 80°C for2 h. The synthesized ZnO NPs were dried at 40°C for 24 h and calcined at 100°C for 1 h.The agarwell diffusionmethodwas used to evaluate ZnONPs for antimicrobial activity ofselected pathogenic strains. A clear zo“ne of inhibitionwasmeasured; 40.05mm± 0.137for Staphylococcus aureus, 36.15 mm ± 0.304 for Escherichia coli and 40.10 mm ± 0.050for Aspergillus niger that were comparably better results than standard antibioticGentamycin that showed 25 and 26mmzone of inhibition for Staphylococcus aureus andEscherichia coli respectively. The minimum inhibitory concentration scored as 9.765µg ±0.00, 9.531µg ± 0.00 and 5000µg ± 0.00 for Staphylococcus aureus, Escherichia Coli andAspergillus niger respectively, was documented low concentration than reported so farconcentrations of green tea ZnO NPs.

Subjects: Bioscience; Food Science & Technology; Physical Sciences; Medicine, Dentistry,Nursing & Allied Health

Shagufta Irshad

ABOUT THE AUTHORShagufta Irshad is an associate professor atDepartment of chemistry, Govt. PostgraduateCollege for Women, Gulberg Lahore, Pakistan. Sheis a PhD in Biochemistry from Institute ofBiochemistry and Biotechnology, University ofVeterinary and Animal Sciences, Lahore, Pakistan.She received her MSc and MPhil degrees fromDepartment of Chemistry, Govt. CollegeUniversity, Lahore, Pakistan. Her research inter-ests include essential amino acids production byFermentation, phytochemical studies, greensynthesis of nanoparticles, characterization,antioxidant, antimicrobial and toxicityevaluation.

PUBLIC INTEREST STATEMENTSince plant extracts having bioactive constituentsare commonly used in pharmaceutical formula-tions due to their medicinal applications. Thesebioactive constituents can be involved in redu-cing and capping of metal ions for the synthesisof nanoparticles (NPs). A few reported works isavailable on the biosynthesis of some metals NPslike MgO, TiO2, CuO, FeO2, Al2O3 and ZnO. Fromall these, ZnO NPs has got great attention inrecent years with enormous applications asthese are easy to synthesize, cheap and safemethod. Plant mediated NPs free from toxins canhave vast scope in the field of biomedicalscience, food and cosmetics industries. TheseNPs are most promising as they show goodantibacterial and antifungal properties due totheir large surface area to volume ratio, becamea current interest in the researches due to thegrowing microbial resistance against metal ions,antibiotics and the development of resistantstrains.

Irshad et al., Cogent Chemistry (2018), 4: 1469207https://doi.org/10.1080/23312009.2018.1469207

© 2018 The Author(s). This open access article is distributed under a Creative CommonsAttribution (CC-BY) 4.0 license.

Received: 12 December 2017Accepted: 20 April 2018First Published: 09 May 2018

*Corresponding author: ShaguftaIrshad, Department of Chemistry,Government College for WomenGulberg, Affiliated Lahore CollegeUniversity, Lahore, PakistanE-mail: shaguftairshad16@gmail.com

Reviewing editor:Junli Yang, Lanzhou Institute ofChemical Physics, China

Additional information is available atthe end of the article

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Keywords: green tea; leaves; mediated; nanoparticles; antimicrobial

1. IntroductionNanotechnology is emerging as multidisciplinary field of science in which a wide range of metalnano nanoparticles (NPs) have been synthesized. The produced NPs have unique size with moresurface area to volume ratio that promoted their reactivity with the surrounding molecules(Gunalana, Sivaraja, & Rajendran, 2012). Therefore conventionally both physical and chemicalmethods are used to synthesize them, however these methods have various demerits includingexpensive, toxic by-products, critical conditions of temperature and pressure and long-time ofreactions etc (Geraldes et al., 2016). Whereas green synthesis of NPs; involve nontoxic, cheapand broadly available plant sources that are environment friendly (Salem, Albanna, & Awwad,2016). Those medicinal plants were preferably used in the synthesis of NPs that already documen-ted for biomedical properties and having immense range of natural products (Agarwal, Kumar, &RajeshKumar, 2017). These bioactive phytochemicals are reacted to reduce metals into metal oxideand showing good stability in the formation of NPs (Mishra & Sharma, 2015). Noble metals like gold(Au) and silver (Ag) have been extensively used in biosynthesis NPs and medically evaluated.However very few reported work was available on inorganic metals such as Ti, Mg, Fe, Zn, S andAl. Among these metals; ZnO has got excellent position due its wide applications in various fields ofscience (Dhanemozhi, Rajeswari, & Sathyajothi, 2017).

ZnO NPs were reported to have better UV protection and enhanced opaqueness than TiO2 NPs thatwas previously used for UV protections (Sundrarajan, Ambika, & Bharathi, 2015). These NPs showedelevated catalytic, photochemical and antimicrobial properties (Awwad, Albiss, Ahmad, 2014). TheseNPs were documented to rupture the lipid bilayers of bacterium and fungal cell wall and revealedsignificant antibacterial and antifungal activity (Senthilkumar & Sivakumar, 2014). Beside this; ZnONPs were also evaluated to have good antioxidant, anti- diabetic and anticancer property (Pattanayak& Nayak, 2013). Thus, these NPs depicted tremendous applications in biomedicines and microelec-tronics (Hasan, Das, Khan, Hasan, & Rahman, 2009). Production of ZnO NPs is still infancy stage;therefore there is a gigantic scope of this work to synthesize and evaluate its antimicrobial activity.

In this study, dried Green tea leaves were used to synthesize ZnO NPs. It is scientifically knownas “Camellia Sinensis” famous for its Phenolic contents and high antioxidant activity(Saravanakkumar, Sivaranjani, Umamaheswari, Pandiarajan, & Ravikumar, 2016). This plantbelongs to family Theaceae and is rich in bioactive phytochemicals that refers it as anti-septic,anticancer and antimicrobial agent for valuable medical drugs (Rani, Nagpal, Gullaiya, Madan, &Agrawal, 2014). Consequently, these properties are enhanced in the form of ZnO NPs; where thesebioactive components are locked while reducing and capping of NPs (Malapermal, Mbatha, Gengan,& Anand, 2015). During the present work ZnO NPs were synthesized by using leave extract ofCamellia sinensis (C. sinensis) and its antibacterial and antifungal activity was evaluated. Furtherproduced ZnO NPs were also characterized by UV–visible, FTIR, XRD and SEM.

2. Materials and methodsThe plant material was procured from the local nursery near Gulberg and identified by Dr. ZaheerUddin Khan, Distinguished Professor, Botany department, Govt. College University, Lahore,Pakistan. The fresh leaves were separated and dried under shade for 5 days. The dried leaveswere grinded into power and stored in air tight jar for further work.

2.1. Synthesis of ZnO NPsLeave extract was prepared by following Senthilkumar and Sivakumar (2014) with some modifica-tions as; 10 g of dried leaves were heated in 100 mL deionized water at 80°C with continuous stirringfor 2 h. It was cooled at room temperature (25°C) and filtered by using whatman filter paper No. 40.Then clear extract was obtained by centrifugation at 4000 rpm for 10 min. Zinc acetate dihydratesolution (0.2 M) was freshly prepared and 230 mL was added to 100 mL of leave extract. With the

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instant formation of pale yellow ZnO NPs, the reacted solution was dried at 40°C for 24 h and browndried crystals were attained. These crystals were further calcined for 1 h at 100°C, cooled, weighedand stored in brown bottles for future investigations. Freshly prepared 100 mL leave extract was alsodried at 40°C for 24 h for further analysis.

2.2. Antimicrobial studiesThe synthesized ZnO NPs were evaluated for antimicrobial activity; well diffusion method (Hasanet al., 2009) was applied to screen famous pathogenic microbes. For antibacterial assay, grampositive bacteria Staphylococcus aureus (S. aureus) and gram negative bacteria Escherichia. coli(E. coli) were spread uniformly on nutrient agar plates having wells of 4 mm. ZnO NPs (100 mg/mL)normal solution was introduced in the wells under sterilized conditions and incubated at 37°C for24 h. The zone of inhibition (mm) around well was measured; same procedure was applied forpathogenic fungus: Aspergillus niger (A. niger) during antifungal assay. All the bacterial and fungalstrains used in this study were obtained from the Department of Microbiology, University OfVeterinary and Animal Sciences, Lahore. Gentamycin (100 mg/mL) was used as standard antibioticagainst bacterial strains and zone of inhibition (mm) was measured.

2.3. Minimum inhibitory concentrationMinimum inhibitory concentration (MIC) was measured following well diffusion method in repli-cates (N = 3) for each microbial strain. This standard method for antimicrobial assay (Mishra,Sasmal, & Shrivastava, 2012) was employed in tube serial dilutions of ZnO NPs (100mg/mL) inbacterial and fungal growth media. The pathogenic microbes were incubated at 37°C for 24 h andlowest inhibitory concentration was scored. All the experiments were applied in replicates (N = 3)and mean value with standard deviation (SD) was calculated by descriptive analysis on SPSSstatistics 17.0.

2.4. CharacterizationThe presence or absence of important bioactive molecules like alkaloids, flavonoids, phenols,carbohydrates, protein, terpenes and saponins were investigated by performing reported tests(Tiwari, Kumar, Kaur, Kaur, & Kaur, 2011). The green tea mediated ZnO NPs were scanned for UV–visible spectroscopy between 200 and 500 nm to determine absorption maxima. The differentfunctional groups in crude dried leave extract and ZnO nanoparticles were identified by FTIR(Agarwal et al., 2017) performed at Centre of Applied Chemistry, PCSIR Laboratories complex,Lahore, Pakistan. XRD and SEM analysis was achieved at Department of Chemistry, SBASSE LahoreUniversity of Management Sciences, Lahore, Pakistan.

3. Results and discussionThe green synthetic method of ZnO NPs is a recent approach that is the elucidation of a cheap,eco-friendly and scale up synthetic method. Medically important plants have such phytochemicalswhich act to stabilize and reduce metal oxides for the synthesis of NPs with controlled shape andsize (Rani et al., 2014). Further such famous phytochemicals are involved in the inhibition mechan-ism of microbial pathogenic growth (Zhang, Ding, Povey, & York, 2008). Therefore, such plantmediated NPs free from toxins can have vast scope in the field of biomedical science, food andcosmetics industries, consequently this study now become a foremost area of research. In thispresent study, for the green synthesis of ZnO NPs; dried grinded leaves of C. sinensis were used toprepare extract and 230 mL of 0.2 M solution of Zinc acetate dihydrate was poured in 100 mL offresh leave extract. Pale yellow ZnO nanoparticles were instantly appeared that grew larger withinseconds and finally settled down leaving supernatant layer which was also taken for phytochem-ical investigation. The visual diagram of all the procedure in the form of flow sheet was presentedin Figure 1. Further the produced NPs were dried at 40°C in oven for 24 h and dried brown NPs wereobtained by calcined at 100°C for 1 h. Thus green synthesized ZnO NPs were weighed as 9.1g/100 mL of leave extract. This is the first time reported concentration of green tea ZnO NPs withcomplete scheme of work.

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3.1. Antimicrobial activityThe microbicidal activity of synthesized NPs (100mg/mL) was measured against pathogenic strainsand found 40.05 mm ± 0.137 zone of inhibition against S. aureus, 36.15 mm ± 0.304 for E. coli and40.10 mm ± 0.050 for A. niger shown in Figure 2. These results documented better antibacterialactivity of produced ZnO NPs than the standard antibiotic; Gentamycin (100 mg/mL) that showedzone of inhibition 25 mm against S. aureus and 26 mm for E. coli. The biocidal action of ZnO NPsrevealed their mechanism that involve the disruption of cell membrane with the action of Zn+2 onits surface that ultimately cause the death of microbes (Gunalana et al., 2012). Further standardprotocols were followed to measure MIC for the above mentioned strains and observed concen-trations for S. aureus was 9.765 µg ± 0.00, E. coli was 19.531 µg ± 0.00 and A. niger was 5000 µg ±0.00. This minimum concentration of ZnO NPs required for antimicrobial activity as given in Table 1depicted the cost effectiveness of initially green synthesized ZnO NPs (91 g/100 mL) and itsapplication in antimicrobial activity. Some researchers also studied mode of inhibitory action ofZnO NPs for microbial growth, as Mishra et al. (2012) documented cell damage caused by theseNPs with the presence of protein and nucleic acid of nutrient agar, Femi, Prabha, Sudha, Devibala,and Jerald (2011) demonstrated the surface binding of NPs with thiol group of glycoproteins onethe cell wall of microbes and decreases the permeability with subsequently lyses of cell to inhibitcell growth. Gunalana et al. (2012) also explained the damage of cell membrane with leakage ofprotein, minerals and genetic material by the interaction of ZnO NPs with microbial strains.

Figure 1. Flow sheet diagramrepresenting green synthesis ofZnO NPs: (a) dried grind leaveof C. sinensis, (b) leave extract,(c) synthesis of ZnO NPs, (d)settled ZnO NPs having super-natant layer, (e) drying of ZnONPs at 40°C and (f) dried andcalcined at 100°C ZnO NPs.

(a) (b) (c)

Figure 2. Zone of inhibition(mm) measured for antimicro-bial activity of Green tea ZnONPs evaluated on (a)Staphylococcus aureus (b)Escherichia. coli (c) Aspergillusniger.

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Senthilkumar and Sivakumar (2014) reported no zone of inhibition for E. coli, 5.300 ± 0.570 forS. aureus and 3 ± 1.00 for A. niger against C. sinensis ZnO NPs. Antimicrobial activity of black tea(C. sinensis) extract was performed by Vasudeo and Sonika (2009) for different pathogen bacterialstrains and found zone of inhibition 14 ± 2 for both E. coli and S. auerus. The MIC calculated forchloroform tea extract was 25 µg/mL. Boran et al. (2015) studied the antibacterial activity of Teaseeds against some famous pathogenic strains and reported the significant biocidal property ofseeds. During this study C. sinensis NPs depicted better antimicrobial activity than other research-ers’ findings and with low MIC. The high zone of inhibition with MIC was in agreement withdocumented literatures that ZnO NPs rupture lipid bilayer of bacterial and fungal cell wall withthe ultimate death of microbes (Saravanakkumar et al., 2016).

3.2. CharacterizationSome qualitative tests were performed to determine the presence or absence of importantbioactive compounds in the crude leaves extract and in supernatant layer after ZnO NPs settle-ment; like alkaloids, flavonoids, carbohydrates, proteins, terpenes, phenols and saponins. Therewas strong presence of all above bioactive phytochemicals in leave extract whereas weak pre-sence of most phytochemicals was noticed in supernatant layer. During screening proteins andphenols were absent in supernatant layer, although saponins were strongly present in bothextracts. The weak presence or absence of these natural products was in agreement with reportedliterature (Uzunalic et al., 2006) that bioactive constituents are involved in reduction and cappingof metal oxides during NPs synthesis (Malapermal et al., 2015). Absence of protein might berelated with its association with ZnO NPs synthesis and stabilization (Moghaddam et al., 2017).

3.3. UV–visible and FTIR analysisThe spectrum obtained by UV–visible spectroscopy as shown in Figure 3 represented characteristicpeak of pure ZnO NPs with absorption maxima of 350 nm. The peak broadening was between 320and 380 nm which was in good agreement with the reported literature (Awwad et al., 2014; Dattaet al., 2017; Saravanakkumar et al., 2016). No other peak observed in spectrum indicating highpurity and crystallinity of ZnO NPs (Santhoshkumar, Kumar, & Rajeshkumar, 2017).

Further FTIR of crude leaves extract and ZnO NPs also depicted the compatible results with otherresearchers’ findings and different pattern of peaks were observed in both dried moieties as shownin Figure 4.

There is a broad stretch between 3000 and 3600 cm−1 with absorption maxima at 3320 cm−1

that ascribed the stretching frequencies of amino and hydroxyl of alcohols and phenols. Anabsorption peak at 2910 cm−1 represented the symmetric and asymmetric stretching of aliphaticfunctional group (CH3 and CH2). When these two peaks are compared with the IR- spectrum of ZnONPs, these stretching became narrow with decrease of peak broadening in NPs spectrum might beassociated that these functional groups are used to reduce Zn+2 into its oxide. Further when bothspectrums compared it was revealed to have visible difference between absorption maxima and

Table 1. Zone of inhibition measured by well-diffusion method and MIC for antimicrobial

activity of green synthesized ZnO Nps against pathogenic microbial strains of clinical sources

Microbial strain Aq. extract ofCamellia sinensis

leaves(100 mg/mL)

ZnO NPs ofCamellia sinensis

leave(100mg/mL) ± SD

Gentamycin (std.antibiotic)

(100 mg/mL)

MIC ± SD

Staphylococcusaureus

No zone 40.05 mm ± 0.137 25 mm 9.765 µg ± 0.00

Escherichia coli No zone 36.15 mm ± 0.304 26 mm 19.531 µg ± 0.00

Aspergillus niger No zone 40.10 mm ± 0.05 – 5000 µg ± 0.00

Where no. of treatments (N) = 3, standard deviation = SD.

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stretching frequencies. As ZnO NPs spectrum have two prominent sharp peaks at 610 and520 cm−1 of C–alkyl chloride and hexagonal ZnO (Nalvolthula, Merugu, & Rudra, 2014) that istotally absent in crude leaves extract spectrum. Moreover two weak peaks at 1650 cm−1 (carbonylfunctional group in amide I and II) and 1430 cm−1 (C–N stretching frequencies of amide I and –

CH2– scissoring vibrations of proteins) appeared prominent and sharp in NPs spectrum. Theseresults are in agreement with reported findings that proteins stabilize the NPs and also justifiedthe absence of protein in supernatant layer of ZnO NPs during phytochemical studies. Twoprominent peaks at 1017 and 990 cm−1 corresponded to C–O vibrational stretching frequenciesof alcohol and amino acids (Salem et al., 2016) and C–N stretch of amine respectively found incrude leave spectrum whereas two weak peaks appeared at 1050 and 960 cm−1 in ZnO NPs

Figure 3. UV–visible spectrumof green tea ZnO NPs showingcharacteristic absorptionbetween 320 and 380 nm andλmax at 350 nm.

Figure 4. FTIR of crude driedextract of Camellia sinensis andits ZnO NPs representing char-acteristic functional groupspeaks.

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spectrum. The presence of some sharp and prominent peaks in crude extract spectrum andabsence or weak presence in ZnO NPs spectrum suggested that those functional groups perform-ing the job of capping, dispersing and stabilizing agents for NPs.

3.4. XRD studiesThe spectrum of green synthesized ZnO NPs is given in Figure 5(b) and observed prominent peaks thatwere in fair agreement with reported literature of international Centre of Diffraction Data card (JCPDS-36–1451). Whereas diffractogram of green tea leaves extract (Figure 5a) depicted no such peak patternwas found in ZnO NPs, moreover no characteristic peaks of ZnOwas noticed. Both spectrumswere quitedifferent and revealed presence of ZnO NPs formation in Figure 5(b) after reacting extract with Zincacetate. The peaks in ZnO NPs spectrum were appeared with 2θ ranging from 20 to 70 with noticeablediffraction angles of 23.2°, 24.1°, 26.2°, 28.1°, 32.2°, 34.45°, 36.29°, 46.22°, 55.19° and 67.15° that indexedsize of crystals with prominent indices plane of ZnO (hkl) as (100), (002), (101), (102), (110) and (112).Thus average size of NPs was ranged between 30 and 40 nm, calculated by Debye–Scherrer equation(Saravanakkumar et al., 2016). These results of XRD were compatible with reported researchers’ workthat confirmed the prepared ZnO sample is highly crystalline, having hexagonal wurtzite crystallinestructure calculated by Bragg equation, λ = 2dsinθ (Agarwal et al., 2017). The typical XRD patternrevealed that the sample contains zinc oxide nanoparticles. XRD pattern of synthesized metal oxidenanoparticles showed a high crystallinity of sample level with diffraction angles which correspond to thecharacteristic face centred cubic. XRD patterns were analysed to determine peak intensity, position andwidth ((Moghaddam et al., 2017). Vennila, Jesurani, Priyadharshini, and Ranjani (2016) also reportedsimilar results of XRD Diffractogram with diffractions angles at 23.4°, 27.9°, 35.3° and 44.3°; indexed(111), (220), (101) and (311) plane that corresponded to face centred cubic ZnO plane. Moreover manyresearchers found XRD diffractogram in good agreement with data cards JCPDS-36–1451 (Awwad et al.,2014; Saravanakkumar et al., 2016), JCPDS-5–0566 (Vidya et al., 2013), JCPDS-89–1397 (Joel &Badhusha, 2016) and JCPDS-01–079- 0207 ((Nalvolthula et al., 2014).

3.5. SEM analysisThe images gained by SEM analysis represented the morphologies of green tea mediatedresultant ZnO nanosheets; as Figure 6(a) showed the surface image of primary particlesmerged together to yield bigger sized secondary particles. Although larger quantities of phy-tochemicals in leaves extract synthesized nanosheets with quite surface; Figure 6(b–d) demon-strated pretty dense morphology of nanoflowers randomly oriented overlapping. Severalthinner sheets aggregated to form nanosheet networks, where individual sheets seem tohave lateral dimension of less than 1 µm. The present results of SEM are in good agreementwith Awwad et al. (2014) documented green synthesized ZnO nanosheets and nanoflowerswith average size 500 nm and average thickness of 8 nm. Whereas Saravanakkumar et al.(2016) found the images of nanostructures that are highly aggregated, irregular as well asuniform hexagonal plates. Datta et al. (2017) revealed biosynthesized NPs’ SEM results asirregular structure of radical, cylindrical and spherical particles aggregated in small cluster.

(a) (b)

0

1000

2000

3000

4000

5000

6000

7000

20 30 40 50 60 70

inte

nsit

y

2θ (Degree)

Figure 5. XRD diffractograms:(a) green tea leaves extract (b)green tea ZnO NPs.

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4. ConclusionThus ZnO nano particles were synthesized by using green tea leaves extract that effectively inhibitmicrobial growth. Moreover during characterization UV–visible spectral peak at 350 nm confirmedthe purity of ZnO NPs and FTIR results documented clearly the capping, reducing and stabilizingphytochemicals found in green tea. XRD diffractogram revealed characteristic peak of ZnO NPswith size range 30–40nm those coalesced to organize in nanosheets as depicted in SEM images.

FundingThe authors received no direct funding for this research.

Competing interestsThe authors declare no competing interests.

Author detailsShagufta Irshad1

E-mail: shaguftairshad16@gmail.comAmna Salamat1

E-mail: amna.parcels@gmail.comAftab Ahmed Anjum2

E-mail: aftab.anjum@uvas.edu.pkSaba Sana2

E-mail: sabasana22@gmail.comRahman ShahZaib Saleem3

E-mail: rahman.saleem@lums.edu.pkORCID ID: http://orcid.org/0000-0002-9615-4471Azra Naheed1

E-mail: azrahunza@gmail.comAsia Iqbal4

E-mail: asia.iqbal@uvas.edu.pk1 Department of Chemistry, Government College forWomen Gulberg, Affiliated Lahore College University,Lahore, Pakistan.

2 Department of Microbiology, University of Veterinary andAnimal Sciences, Lahore, Pakistan.

3 Department of Chemistry, SBASSE Lahore University ofManagement Sciences, Lahore, Pakistan.

4 Department of Wildlife and Ecology, University ofVeterinary and Animal Sciences, Lahore, Pakistan.

Figure 6. SEM images of GreenTea mediated ZnO nanosheets:(a) surface image ofnanosheets (b–d) numerousthinner sheets accumulated toform a nanosheet networks.

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Citation informationCite this article as: Green tea leaves mediated ZnOnanoparticles and its antimicrobial activity, ShaguftaIrshad, Amna Salamat, Aftab Ahmed Anjum, Saba Sana,Rahman ShahZaib Saleem, Azra Naheed & Asia Iqbal,Cogent Chemistry (2018), 4: 1469207.

Cover imageSource: Authors.

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